21st.dev Magic MCP vs build123d-mcp

A side-by-side comparison of two Design & Media servers — tools, transport, auth, maintenance, and copy-paste config for each.

	21st.dev Magic MCP Generate beautiful, modern UI components from natural-language descriptions inside your IDE. Unverified stdio (local) API key TypeScript	build123d-mcp Exposes build123d CAD operations as MCP tools so AI assistants can build, inspect, and iterate on 3D geometry interactively. Unverified stdio (local) No auth Python
Category	Design & Media	Design & Media
Language	TypeScript	Python
Transport	stdio (local)	stdio (local)
Auth	API key	None
GitHub stars	5.2k	25
Last commit	5 months ago	1 month ago
Verified
Actively maintained
Install	`npx @21st-dev/cli@latest install <client> --api-key <key>`	`pip install build123d-mcp`
Repo	Open	Open

Verdict

Pick 21st.dev Magic MCP if you want the official, vendor-maintained server, and you prefer the more popular, battle-tested option.

Pick build123d-mcp if you want zero-setup with no API key, and you need the broadest set of tools.

Add 21st.dev Magic MCP

Install / run

npx @21st-dev/cli@latest install <client> --api-key <key>

Paste into ~/Library/Application Support/Claude/claude_desktop_config.json

{
  "mcpServers": {
    "21st-dev-magic-mcp": {
      "command": "npx",
      "args": [
        "-y",
        "@21st-dev/magic@latest",
        "API_KEY=\"your-api-key\""
      ]
    }
  }
}

Add build123d-mcp

Install / run

pip install build123d-mcp

Paste into ~/Library/Application Support/Claude/claude_desktop_config.json

{
  "mcpServers": {
    "build123d-mcp": {
      "command": "uv",
      "args": [
        "tool",
        "run",
        "--python",
        "3.12",
        "build123d-mcp@latest"
      ]
    }
  }
}

FAQ

21st.dev Magic MCP or build123d-mcp — which is better?

Pick 21st.dev Magic MCP if you want the official, vendor-maintained server, and you prefer the more popular, battle-tested option. Pick build123d-mcp if you want zero-setup with no API key, and you need the broadest set of tools.

Can I use both 21st.dev Magic MCP and build123d-mcp?

Yes — MCP clients let you enable multiple servers at once. Add both configs to your client's mcpServers and use whichever tool fits the task.

Do 21st.dev Magic MCP and build123d-mcp work with Claude, Cursor and Windsurf?

Both do. Copy the per-client config below into Claude Desktop, Cursor, or Windsurf.

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